This invention relates to sheet supplying apparatuses, and more particularly to a sheet supplying apparatus in which sheets different in size stacked in a single container are taken out one after another by a suction device.
In subjecting X-ray photographic sheet films (hereinafter referred to merely as "films" when applicable) to photographical treatment, X-ray films different in size according to the photographed parts or sections are stored in the same container, and these films are taken out of the container in the order of photographing to thereby be supplied to a photographical treatment device such as a developer.
A conventional apparatus for supplying sheets different in size one after another such as that in the above-described film supplying system is as shown in FIG. 1. In this conventional apparatus, a plurality of suction disks 1 are fixedly arranged using the length, in the lateral direction, of the smallest of the sheets 2 as a reference, and the sheets are taken out by grabbing predetermined portions thereof, which are common for all of the sheets regardless of size, with the suction disks 1.
However, the conventional sheet supplying apparatus thus constructed is disadvantageous in the following respects. First, with the conventional sheet supplying apparatus, the relative grabbing position of the suction disks 1 is varied whenever the sheet size is changed; in other words, the grabbing positions on a large size sheet are relatively closer to its one edge than on a small size sheet. Accordingly, sometimes the large size sheet 2 may not be adequately retained by the suction disks 1 because of the weight of the sheet 2 and the negative pressure caused by the large surface area. Futhermore, even if it is retained by the suction disks, its one end portion will be free and therefore, it may be folded when taken out. Thus, it is difficult to supply the sheets 2 one by one. This difficulty becomes more significant as the difference in width between the sheets 2 is increased. Accordingly, in the case of using the conventional apparatus, the variations in sheet size are limited, and it is essential that both opposite edges of sheets 2 in the stack are correctly aligned. Thus, the conventional sheet supplying apparatus is greatly limited in its practical uses.
Accordingly, an object of the invention is to eliminate all the above-described difficulties accompanying a conventional sheet supplying apparatus. More specifically, an object of the invention is to provide a sheet supplying apparatus which can positively supply sheets different in size one after another without damage to the sheets.
The foregoing object of the invention can be achieved by the provision of a sheet supplying apparatus comprising suction disks for grabbing and retaining each sheet, a pressure reducing source for applying a suction pressure to the suction disks, a driving means for driving the suction disks, to thereby grab and take out sheets different in size one after another, in which apparatus, according to the present invention, a plurality of suction disks for grabbing and retaining a sheet are juxtaposed in a lateral direction of the sheets, and a sheet edge detector for detecting an edge of a sheet to be taken out is provided for each of the suction disks, in such a manner that when the sheet edge detector detects the edge of the sheet, the pressure in the corresponding suction disk is reduced.